CN112739964A

CN112739964A - Refrigerant leak detection system

Info

Publication number: CN112739964A
Application number: CN201980042808.7A
Authority: CN
Inventors: P·V·维纳; J·D·斯卡塞拉; M·J·佩尔科维奇; 陈磊; 田海
Original assignee: Carrier Corp
Current assignee: Carrier Corp
Priority date: 2018-09-06
Filing date: 2019-09-05
Publication date: 2021-04-30
Also published as: EP3847401A1; US11441820B2; SG11202012167SA; EP3847401B1; WO2020051314A1; US20210268875A1; JP2021535349A

Abstract

A method of mitigating refrigerant leakage within a refrigeration system, comprising: detecting leakage of refrigerant from the refrigeration system; closing a first valve to suppress fluid flow of refrigerant between an evaporator and a condenser fluidly connected to the evaporator and operating the compressor to direct another fluid flow of refrigerant from the evaporator to the compressor.

Description

Refrigerant leak detection system

Technical Field

Exemplary embodiments relate to the field of refrigeration systems. And more particularly to transport refrigeration units.

Background

The product may be shipped or stored in a conditioned space, such as a cargo box, truck, or trailer. These conditioned spaces utilize refrigeration units that circulate cooling air within the interior volume. In many cases, refrigeration units use a refrigeration cycle to cool air. Refrigerant from the refrigeration unit may leak into the conditioned space.

Disclosure of Invention

According to an embodiment, a refrigeration system is provided. The refrigeration system includes a compressor, a condenser, an evaporator, a leak sensor, and a controller. The compressor is driven by a power source and has a compressor outlet and a compressor inlet. The condenser has a condenser inlet and a condenser outlet, the condenser inlet being fluidly connected to the compressor outlet. The evaporator has an evaporator inlet fluidly connected to the condenser outlet by a first valve movable between an open position and a closed position, and an evaporator outlet fluidly connected to the compressor inlet. The leak sensor is arranged to provide a signal indicative of the refrigerant. A controller is in communication with the first valve and the compressor. The controller is arranged to receive the signal and is programmed to command the first valve to move toward the closed position in response to the signal indicating refrigerant.

In addition or alternatively to one or more of the features described above, further embodiments may include: the controller is further programmed to output an indicator for display.

In addition or alternatively to one or more of the features described above, further embodiments may include: the controller is further programmed to operate the compressor such that refrigerant within the evaporator is directed toward the compressor.

In addition or alternatively to one or more of the features described above, further embodiments may include: the controller is further programmed to command the compressor to stop operating in response to the fluid pressure between the evaporator outlet and the compressor outlet being less than a threshold pressure.

In addition or alternatively to one or more of the features described above, a further embodiment may include a receiver having a receiver inlet fluidly connected to the condenser outlet, wherein the receiver is arranged to receive refrigerant from the condenser.

In addition or alternatively to one or more of the features described above, further embodiments may include: the controller is arranged to receive the signal and is programmed to command the first valve to move toward the closed position in response to the signal indicating the selected concentration of refrigerant.

In addition or alternatively to one or more of the features described above, further embodiments may include: the controller is further programmed to operate the evaporator fan upon detection of refrigerant.

In addition or alternatively to one or more of the features described above, further embodiments may include a second valve fluidly connecting the evaporator outlet and the compressor inlet, the second valve being movable between an open position and a closed position.

In addition or alternatively to one or more of the features described above, further embodiments may include: the controller is further programmed to operate the compressor such that refrigerant within the evaporator is directed toward the compressor until a suction pressure measurement near an inlet of the compressor is less than ambient pressure.

In addition or alternatively to one or more of the features described above, further embodiments may include: the controller is programmed to command the second valve to move toward the closed position when a suction pressure measurement near the inlet of the compressor is less than ambient pressure.

In addition or alternatively to one or more of the features described above, further embodiments may include a main heating valve fluidly connecting the compressor outlet and the condenser inlet, the main heating valve movable between an open position and a closed position, wherein the controller is programmed to command the main heating valve to move to the open position.

In addition or alternatively to one or more of the features described above, further embodiments may include a hot gas valve fluidly connecting the compressor and the evaporator inlet, the hot gas valve being movable between an open position and a closed position, and wherein the controller is programmed to command the hot gas valve to move to the closed position prior to commanding the first valve to move toward the closed position.

In addition or alternatively to one or more of the features described above, further embodiments may include: the evaporator and the leak sensor are located within a conditioned space of the refrigeration system, and wherein the first valve and the second valve are located outside the conditioned space.

In accordance with another embodiment, a method of mitigating refrigerant leakage in a refrigeration system is provided. The method comprises the following steps: detecting a leakage of refrigerant from the refrigeration system; closing the first valve to inhibit fluid flow of refrigerant between the evaporator and a condenser fluidly connected to the evaporator; and operating the compressor to direct another fluid flow of refrigerant from the evaporator to the compressor.

In addition to or as an alternative to one or more of the features described above, further embodiments may include directing a fluid flow of refrigerant from the compressor to the receiver.

In addition to or as an alternative to one or more of the features described above, further embodiments may include operating an evaporator fan disposed proximate to the evaporator.

In addition to or as an alternative to one or more of the features described above, further embodiments may include ceasing operation of the compressor in response to the evaporator pressure being less than a threshold pressure.

In addition to or as an alternative to one or more of the features described above, further embodiments may include closing a second valve to inhibit fluid flow of refrigerant between the receiver and the condenser.

In addition to or as an alternative to one or more of the features described above, further embodiments may include closing the second valve to inhibit fluid flow of refrigerant between the evaporator and the compressor.

In addition or alternatively to one or more of the features described above, further embodiments may include: the method further comprises the following steps: opening a main heating valve to allow fluid flow of refrigerant between the compressor and the condenser; and closing the hot gas valve to inhibit fluid flow of refrigerant between the compressor and the evaporator.

Drawings

The following description should not be considered limiting in any way. Referring to the drawings, like elements are numbered alike:

FIG. 1 is a schematic diagram of a refrigeration system;

FIG. 2 is a flow chart illustrating a method of mitigating refrigerant leakage of a refrigeration system;

FIG. 3 is a schematic diagram of a refrigeration system;

FIG. 4 is a flow chart illustrating a method of mitigating refrigerant leakage of a refrigeration system; and is

Fig. 5 is a perspective view of a transport system having a refrigeration system (as one non-limiting example) according to embodiments of the present disclosure.

Detailed Description

A detailed description of one or more embodiments of the disclosed apparatus and methods is presented herein by way of illustration, and not limitation, with reference to the accompanying drawings.

Referring to fig. 5, a transport system 420 of the present disclosure is shown. In the illustrated embodiment, the transport system 420 may include a tractor or vehicle 422, the conditioned

space

12, 112, and the refrigeration system 10, 100. The conditioned

space

12, 112 may be towed by a vehicle 422. It should be understood that the embodiments described herein may be applied to conditioned spaces shipped via rail, sea, air, or any other suitable cargo box, and thus the vehicle may be a truck, train, boat, airplane, helicopter, or the like.

The vehicle 422 may include an operator compartment or cab 428 and a vehicle motor 442. The vehicle 22 may be driven by a driver located within the cab, remotely driven by a driver, autonomous, semi-autonomous, or any combination thereof. The vehicle motor 442 may be an electric engine or a combustion engine powered by a combustible fuel. The vehicle motor 442 may also be part of a power drive train or drive system of a trailer system (e.g., conditioned space 12, 112), and thus the vehicle motor 442 is configured to propel the wheels of the vehicle 22 and/or the wheels of the conditioned

space

12, 112. The vehicle motor 442 may be mechanically connected to the wheels of the vehicle 422 and/or the wheels of the conditioned

space

12, 112.

The conditioned

space

12, 112 may be coupled to the vehicle 22 and thus towed or propelled to a desired destination. The conditioned

space

12, 112 may include a top wall 430, a bottom wall 432 opposite and spaced from the top wall 430, two side walls 434 spaced apart and opposite from each other, and opposing front and rear walls 436, 438, with the front wall 436 being closest to the vehicle 422. The conditioned

space

12, 112 may also include a door (not shown) located at the back wall 438 or any other wall. The

walls

430, 432, 434, 436, 438 together define the boundaries of the refrigerated

interior volume

14, 114. Typically, the transport system 420 is used to transport and distribute goods, such as, for example, perishable items and environmentally sensitive items (referred to herein as perishable items). Perishable items may include, but are not limited to, fruits, vegetables, grains, legumes, nuts, eggs, dairy products, seeds, flowers, meat, poultry, fish, ice, blood, pharmaceuticals, or any other suitable cargo requiring cold chain transportation. In the illustrated embodiment, a refrigeration system 10, 100 is associated with the conditioned

space

12, 112 to provide a desired environmental parameter, such as, for example, temperature, pressure, humidity, carbon dioxide, ethylene, ozone, light exposure, vibration exposure, and other conditions, to the refrigerated

interior volume

14, 114. In further embodiments, the refrigeration systems 10, 100 are refrigeration systems capable of providing a desired temperature and humidity range.

Referring to fig. 1, a conditioned space 12 may be provided with a refrigeration system 10, the refrigeration system 10 providing conditioned or cooled air to an interior volume 14 of the conditioned space 12. The conditioned space 12 may include, but is not limited to, a refrigerated trailer, a refrigerated truck, a refrigerated space, or a refrigerated cargo box. The refrigeration system 10 may be adapted to operate using a refrigerant, such as a low global warming potential refrigerant including a1, A2, A2L, A3, and the like. In some cases, refrigerant may leak into the interior volume 14, and there may be a hazard if the concentration of leaked refrigerant within the interior volume 14 exceeds a threshold level. The threshold level may be a lower flammability limit of the refrigerant. The evaporator 24, the portion of refrigerant line 69 near the evaporator outlet 62, and the portion of refrigerant line 64a near the evaporator inlet 60 can be located within the interior volume 14 of the conditioned space 12, and thus can be a source of leakage of refrigerant into the interior volume 14.

The refrigeration system 10 can be a transport refrigeration system, such as a transport refrigeration unit. The refrigeration system 10 includes a compressor 20, a condenser 22, an evaporator 24, and a leak detection system 26, the leak detection system 26 being arranged to detect and mitigate the presence of refrigerant within the interior volume 14.

The compressor 20 is powered or driven by a power source 30. The power source 30 may be an internal combustion engine that drives an electrical generator arranged to power the compressor via the belt or otherwise provide power to the compressor 20 and other components of the refrigeration system 10.

The compressor 20 is arranged to receive refrigerant from the evaporator 24 through a compressor inlet 40. The compressor 20 is arranged to discharge refrigerant through the compressor outlet 42 to the condenser 22 through the receiver 46.

The condenser 22 is arranged to receive a fluid flow of refrigerant from the compressor 20 through a condenser inlet 50 and to discharge the fluid flow of refrigerant to the receiver 46 through a condenser outlet 52. The condenser inlet 50 is fluidly connected to the compressor outlet 42 by a refrigerant line 56.

A fan, such as condenser fan 58, may be associated with condenser 22. A condenser fan 58 is disposed adjacent the condenser 22.

The evaporator 24 is arranged to receive a fluid flow of refrigerant from the condenser 22 through an evaporator inlet 60 and to discharge the fluid flow of refrigerant to the compressor 20 through an evaporator outlet 62. The evaporator inlet 60 is fluidly connected to the condenser outlet 52 through the receiver 46 via refrigerant lines 64a, 64b by a first valve 66 and/or a second valve 76, the second valve 76 being disposed on an opposite side of the receiver 46 from the first valve 66. The evaporator outlet 62 is fluidly connected to the compressor inlet 40 by a refrigerant line 69.

The first valve 66 may be an expansion valve, such as an electronic expansion valve, a movable valve, or a thermal expansion valve. The first valve 66 is movable between an open position and a closed position to selectively inhibit and facilitate fluid flow of refrigerant between the evaporator 24 and at least one of the condenser 22 and the receiver 46. The open position facilitates fluid flow of refrigerant between the evaporator inlet 60 and the condenser outlet 52 through the receiver 46. The closed position inhibits fluid flow of refrigerant between the evaporator inlet 60 and the condenser outlet 52 through the receiver 46 and inhibits fluid flow of refrigerant between the receiver 46 and the evaporator inlet 60.

A fan, such as an evaporator fan 68, may be associated with the evaporator 24. An evaporator fan 68 is disposed adjacent the evaporator 24.

Receiver 46 is fluidly connected to condenser 22 and evaporator 24, and is arranged to receive and store refrigerant based on a position of at least one of first valve 66 and/or second valve 76. The receiver 46 is arranged to receive refrigerant from the condenser outlet 52 through a first receiver inlet 70 via refrigerant line 64 b. In at least one embodiment, the second valve 76 is arranged to selectively facilitate fluid flow between the condenser outlet 52 and the first receiver inlet 70. The second valve 76 may be a movable valve, a solenoid valve, a fluid line service valve, a thermal expansion valve, or an electronic expansion valve. The second valve 76 is movable between an open position and a closed position. The open position facilitates fluid flow of refrigerant between the condenser outlet 52 and the first receiver inlet 70. The closed position inhibits fluid flow of refrigerant between the condenser outlet 52 and the first receiver inlet 70. The receiver 46 is arranged to discharge or provide a fluid flow of refrigerant through the refrigerant line 64a to the evaporator inlet 60 via the first valve 66 through the receiver outlet 74.

The third valve 77 may be arranged to selectively facilitate fluid flow between the compressor outlet 42 and the condenser inlet 50. The third valve 77 may be a movable valve, a check valve, a fluid line service valve, a thermal expansion valve, or an electronic expansion valve. The third valve 77 is movable between an open position and a closed position. The open position facilitates fluid flow of refrigerant between the compressor outlet 42 and the condenser inlet 50. The closed position inhibits fluid flow of refrigerant between the compressor outlet 42 and the condenser inlet 50. Alternatively, the third valve 77 may be interposed in the refrigerant line 69.

The fourth valve 78 may be arranged to selectively promote fluid flow between the evaporator outlet 62 and the compressor inlet 40. The fourth valve 78 may be a movable valve, a check valve, a fluid circuit service valve, a thermal expansion valve, or an electronic expansion valve. The fourth valve 78 is movable between an open position and a closed position. The open position promotes fluid flow of refrigerant between the evaporator outlet 62 and the compressor inlet 40. The closed position inhibits fluid flow of refrigerant between the evaporator outlet 62 and the compressor inlet 40.

In an embodiment, the first valve 66, the second valve 76, the third valve 77, and the fourth valve 78 may be located outside of the regulated space 12.

As previously described, the open position of the first valve 66 facilitates fluid flow of refrigerant between the receiver outlet 74 and the evaporator inlet 60. The closed position of the first valve 66 inhibits fluid flow of refrigerant between the receiver outlet 74 and the evaporator inlet 60.

Leak detection system 26 includes a controller 80 and a leak sensor 82. The leak sensor 82 may be configured to detect the refrigerant, detect a selected concentration of the refrigerant, and/or calculate a concentration of the refrigerant. The controller 80 can be a controller provided with a transport refrigeration unit, or can be a separately provided controller.

Controller 80 is provided with an input communication channel arranged to receive information, data or signals from, for example, compressor 20, power source 30, condenser fan 58, first valve 66, evaporator fan 68, second valve 76, pressure sensor 90, compressor discharge pressure sensor 92, and leak sensor 82. The controller 80 is provided with an output communication channel arranged to provide commands, signals or data to, for example, the compressor 20, the power source 30, the condenser fan 58, the first valve 66, the evaporator fan 68 and the second valve 76. The controller 80 is provided with at least one processor programmed to perform leak detection and/or leak mitigation strategies based on information, data, or signals provided via the input communication channel, and to output commands via the output communication channel.

The leak sensor 82 is arranged to provide a signal to the controller 80 indicative of the concentration, amount, or presence of refrigerant within the interior volume 14. The leak sensor 82 may be disposed proximate the evaporator 24 and/or may be disposed proximate the refrigerant line 69 or any other refrigerant line or component that may leak refrigerant into the conditioned space 12. The leak sensor 82 may also be located near a potential location where refrigerant may collect, such as near the floor of the cargo box 12.

In response to the signal from leak sensor 82 indicating a concentration of refrigerant greater than a threshold concentration or the signal indicating the presence of refrigerant within interior volume 14, controller 80 may perform leak mitigation as shown in the flow chart in fig. 2.

Referring to FIG. 2, and with continued reference to FIG. 1, a method 200 of leak detection in the refrigeration system 10 is illustrated, in accordance with an embodiment of the present disclosure. In an embodiment, the method 200 may be performed by the controller 80. At block 201, if the leak sensor 82 does not detect the presence of refrigerant or a refrigerant concentration greater than a threshold concentration, the method may end and/or continuously check for refrigerant leaks repeatedly. If the leak sensor 82 detects the presence of refrigerant or detects a refrigerant concentration greater than a threshold concentration, the method 200 may continue to block 202. At block 202, the controller 80 may record the leak and the start of the leak mitigation strategy into memory. At block 204, the controller 80 is programmed to output an indicator for display. The indicator may be an audible indicator, a visual indicator, or the like. In at least one embodiment, the controller 80 may transmit information or data indicative of the leak to a driver, an operator, a remote computing system, a remote monitoring system, or a display.

The controller 80 may evaluate the operating states of the various components of the refrigeration system 10 in parallel, substantially simultaneously, or sequentially. At block 210, the controller 80 may evaluate whether the compressor 20 is on and operating (e.g., running). At block 212, the controller 80 may evaluate whether the evaporator fan 68 is on and operating (e.g., running). At block 214, the controller 80 may evaluate the position of the first valve 66.

If the compressor 20 is not running at block 210, the controller 80 may command the compressor 20 to operate at block 220. If the compressor is running at block 210, the method 200 may continue to block 230.

If the evaporator fan 68 is not running at block 212, the controller 80 may command the evaporator fan 68 to operate at block 222. Operation of the evaporator fan 68 may facilitate dispersion or dilution of the refrigerant proximate the evaporator 24. Operation of the evaporator fan 68 may facilitate release or drainage of the refrigerant from within the interior volume 14 toward the external environment. In at least one embodiment, the controller 80 may inhibit the evaporator fan 68 from operating if the evaporator fan 68 is not running at block 212. Inhibiting the operation of the evaporator fan 68 prevents the refrigerant from being released or discharged into the external environment. If the evaporator fan 68 is running at block 212, the method 200 may continue to block 230.

If the first valve 66 is open at block 214, the controller 80 may command the first valve 66 to move toward the closed position at block 224. The closing of the first valve 66 inhibits fluid flow of refrigerant between the receiver outlet 74 and the evaporator inlet 60. The closing of the first valve 66 substantially inhibits the delivery of refrigerant to the evaporator 24, which may be a source of refrigerant leakage into the interior volume 14. If at least the first valve 66 is in the closed position, the method may include block 230.

The closing of the first valve 66 enables the compressor 20 to evacuate the evaporator 24 to slow or stop the leakage of refrigerant into the interior volume 14. The compressor 20 operates with the first valve 66 closed such that fluid flow of refrigerant from the evaporator 24 is directed through the evaporator outlet 62 toward the compressor inlet 40 via refrigerant line 69. Removing refrigerant from the evaporator 24 may be referred to as evacuation of the evaporator 24. The compressor 20 directs a fluid flow of refrigerant from the evaporator 24 through the compressor outlet 20 into the receiver 46 to pass through the condenser inlet 50 and out the condenser outlet 52 toward the first receiver inlet 70 such that the refrigerant is stored within the receiver 46. The closing of the first valve 66 inhibits the delivery of refrigerant present within the receiver 46 to the evaporator 24. In at least one embodiment, if the second valve 76 is closed, the compressor 20 may evacuate the evaporator 24 and direct a fluid flow of refrigerant from the evaporator 24 through the compressor 20 and toward the condenser 22. The refrigerant flow is directed into condenser 22 through condenser inlet 50 and is inhibited from flowing toward receiver 46 due to second valve 76 being in a closed position. The compressor 20 may be provided with a backflow shutoff valve such that refrigerant received by the condenser 22 is retained or received within the condenser 22 and/or between the compressors 20 so as to be unable to flow back through the compressor outlet 42 toward the compressor inlet 40.

The method 200 may move to block 230 or 231. At block 230, the method 200 may evaluate whether a suction force, such as a suction pressure less than ambient pressure, is present within the refrigerant line 69 extending between the evaporator 24 and the compressor 20. In such an embodiment, the pressure sensor 90 is configured to detect the pressure within the refrigerant line 69 and communicate the detected pressure to the controller 80. At block 230, alternatively, the method may evaluate a fluid pressure within evaporator 24 (e.g., an evaporator pressure) and determine whether the fluid pressure within evaporator 24 is less than a threshold pressure. In such embodiments, the pressure sensor 90 is disposed within or proximate to the evaporator 24. If the suction pressure is less than the ambient pressure or the evaporator pressure is less than the threshold pressure, the method 200 may continue to block 232. If the suction pressure is greater than the ambient pressure or the pressure within the evaporator 24 is greater than the threshold pressure, the method may return to block 210, block 212, and/or block 214.

Alternatively, if compressor discharge pressure is utilized instead of suction pressure, the method may move to block 231. For example, if the fourth valve 78 is not present in the refrigeration system 10, the compressor discharge pressure may be utilized. At block 231, the method 200 may evaluate whether there is a discharge pressure at the compressor outlet 42 that is greater than a selected pressure within the refrigerant line 56 extending between the compressor 20 and the condenser 22. In such an embodiment, the compressor discharge pressure sensor 92 is configured to sense the pressure within the refrigerant line 56 and communicate the sensed pressure to the controller 80. If the compressor discharge pressure is greater than the selected pressure, the method 200 may continue to block 232. If the compressor discharge pressure is not greater than the selected pressure, the method may return to block 210, block 212, and/or block 214.

At block 232, if the second valve 76 is in the open position, the controller 80 may command the second valve 76 to close such that refrigerant within the receiver 46 is inhibited from escaping from the receiver 46 and flowing toward the evaporator 24 and/or the condenser 22. At block 334, the refrigeration system 110 is turned off.

The leakage mitigation strategy utilizing the evacuation process greatly reduces the risk of the refrigerant reaching the lower flammability limit by removing the refrigerant from the evaporator 24 and storing it within at least one of the receiver 46 or the condenser 22 located outside of the interior volume 14. The leakage mitigation strategy may also dilute or disperse refrigerant that may be present within the interior volume 14 of the conditioned space 12. If the refrigerant leak is in a region that is not exposed to the interior volume 14, the refrigerant may dissipate by itself. Further, operation of the condenser fan 58 may facilitate shedding or dilution of the refrigerant proximate the condenser 22 and may be utilized at any time during the method 200.

Referring to fig. 3, a refrigeration system 110 having a hot line 192 for hot gas bypass is shown in accordance with an embodiment of the present disclosure. In fig. 3, a conditioned space 112 is shown that provides conditioned or cooled air to an interior volume 114 of the conditioned space 112. The conditioned space 112 may include, but is not limited to, a refrigerated trailer, a refrigerated truck, a refrigerated space, or a refrigerated cargo box. The refrigeration system 110 may be adapted to operate using a refrigerant, such as a low global warming potential refrigerant including a1, A2, A2L, A3, and the like. In some cases, the refrigerant may leak into the internal volume 114, and there may be a hazard if the concentration of leaked refrigerant within the internal volume 114 exceeds a threshold level. The threshold level may be a lower flammability limit of the refrigerant. The evaporator 124, the portion of refrigerant line 169 proximate the evaporator outlet 162, and the portion of refrigerant line 164 proximate the evaporator inlet 60 may be located within the interior volume 114 of the conditioned space 112, and thus may be a potential source of leakage of refrigerant into the interior volume 114.

The refrigeration system 110 can be a transport refrigeration system, such as a transport refrigeration unit. The refrigeration system 110 includes a compressor 120, a condenser 122, an evaporator 124, and a leak detection system 126, the leak detection system 126 being arranged to detect and mitigate the presence of refrigerant within the interior volume 114.

The compressor 120 is powered or driven by a power source 130. The power source 130 may be an internal combustion engine that drives an electrical generator arranged to provide power to the compressor 120 and other components of the refrigeration system 110.

The compressor 120 is arranged to receive refrigerant from the evaporator 124 through a compressor inlet 140. The compressor 120 is arranged to discharge refrigerant through a compressor outlet 142 to the condenser 122.

The condenser 122 is arranged to receive a fluid flow of refrigerant from the compressor 120 through a condenser inlet 150 and to discharge the fluid flow of refrigerant to the evaporator 124 through a condenser outlet 152. The condenser inlet 150 is fluidly connected to the compressor outlet 142 by a refrigerant line 156.

An oil separator 186 may be located in refrigerant line 156 between the compressor 120 and the condenser 122 to remove oil from the refrigerant exiting the compressor outlet 142 and direct the oil back to the rotating components of the compressor 120.

A fan, such as condenser fan 158, may be associated with the condenser 122. The condenser fan 158 is disposed proximate the condenser 122.

The evaporator 124 is arranged to receive a fluid flow of refrigerant from the condenser 122 through an evaporator inlet 160 and to discharge the fluid flow of refrigerant to the compressor 120 through an evaporator outlet 162. The evaporator inlet 160 is fluidly connected to the condenser outlet 152 by a refrigerant line 164. The evaporator outlet 162 is fluidly connected to the compressor inlet 140 by refrigerant line 169.

A first valve 166 may be located in refrigerant line 164 between the condenser 122 and the evaporator 124. In at least one embodiment, the first valve 166 is arranged to selectively facilitate fluid flow between the condenser outlet 152 and the evaporator inlet 160. The first valve 166 may be an expansion valve, such as an electronic expansion valve, a movable valve, a solenoid valve, or a thermal expansion valve. The first valve 166 is movable between an open position and a closed position to selectively inhibit and facilitate fluid flow of refrigerant between the evaporator 124 and the condenser 122. The open position facilitates fluid flow of refrigerant between the condenser outlet 152 and the evaporator inlet 160. The closed position inhibits fluid flow of refrigerant between the condenser outlet 152 and the evaporator inlet 160 through refrigerant line 164.

A fan, such as an evaporator fan 168, may be associated with the evaporator 124. An evaporator fan 168 is disposed proximate the evaporator 124.

A second valve 176 may be located in refrigerant line 169 between the evaporator 124 and the compressor 120. In at least one embodiment, the second valve 176 is arranged to selectively facilitate fluid flow between the evaporator outlet 162 and the compressor inlet 140. The second valve 176 may be a movable valve, a solenoid valve, a check valve, a fluid line service valve, a thermal expansion valve, or an electronic expansion valve. The second valve 176 is movable between an open position and a closed position. The open position promotes fluid flow of refrigerant between the evaporator outlet 162 and the compressor inlet 140. The closed position inhibits fluid flow of refrigerant between the evaporator outlet 162 and the compressor inlet 140. In an alternative embodiment, a second valve 176 may be interposed between the compressor outlet 142 and the condenser inlet 150.

In an embodiment, the first and

second valves

166, 176 may be located outside of the regulated space 112.

A main heating valve 196 may be located in refrigerant line 156 between the compressor 120 and the condenser 122. In at least one embodiment, the main heating valve 196 is arranged to selectively facilitate fluid flow between the compressor outlet 142 and the condenser inlet 150. The main heating valve 196 may be a movable valve, a fluid line service valve, a thermal expansion valve, or an electronic expansion valve. The main heating valve 196 is movable between an open position and a closed position. The open position facilitates fluid flow of refrigerant between the compressor outlet 142 and the condenser inlet 150. The closed position inhibits fluid flow of refrigerant between the compressor outlet 142 and the condenser inlet 150.

A heat line 192 may fluidly connect compressor 120 and refrigerant line 164 proximate evaporator inlet 160. During a heating mode of the refrigeration system 110, the heat line 192 may convey hot gas from the compressor 120 to the evaporator inlet 160, which may help defrost the evaporator and/or warm the interior volume 114.

The hot gas valve 194 may be located in the hot line 192 between the compressor 120 and the evaporator 124. In at least one embodiment, the hot gas valve 194 is arranged to selectively facilitate fluid flow between the compressor outlet 156 and the evaporator inlet 160. Hot gas valve 194 may be a movable valve, a fluid line service valve, a thermal expansion valve, or an electronic expansion valve. Hot gas valve 194 is movable between an open position and a closed position. The open position promotes fluid flow of hot gas refrigerant between the compressor outlet 156 and the evaporator inlet 160. The closed position inhibits fluid flow of hot gas refrigerant between the compressor outlet 156 and the evaporator inlet 160.

The refrigeration system 110 may include a check valve 128 in a refrigerant line 164 between a first valve 166 and the evaporator 160, as shown in fig. 3. The refrigeration system 110 may also include an expansion valve 184 in refrigerant line 164 between the check valve 128 and the evaporator 160, as shown in fig. 3. Refrigeration system 110 may additionally include a pressure sensor 190 located within a refrigerant line 169 interposed between evaporator 124 and compressor inlet 140.

The leak detection system 126 includes a controller 180 and a leak sensor 182. The leak sensor 82 may be configured to detect the refrigerant, detect a selected concentration of the refrigerant, and/or calculate a concentration of the refrigerant. A leak sensor 182 may be located within the conditioned space 112. The controller 180 may be a controller provided with the transport refrigeration unit, or may be a separately provided controller.

The controller 180 is provided with an input communication channel arranged to receive information, data or signals from, for example, at least one of the compressor 120, the power source 130, the condenser fan 158, the first valve 166, the evaporator fan 168, the second valve 176 and the leak sensor 182. The controller 180 is provided with an output communication channel arranged to provide commands, signals or data to, for example, the compressor 120, the power source 130, the condenser fan 158, the first valve 166, the evaporator fan 168, the pressure sensor 190 and the second valve 176. The controller 180 is provided with at least one processor programmed to perform leak detection and/or leak mitigation strategies based on information, data, or signals provided via the input communication channel, and to output commands via the output communication channel.

The leak sensor 182 is arranged to provide a signal to the controller 180 indicative of the concentration, amount, or presence of refrigerant within the internal volume 114. The leak sensor 182 may be disposed proximate the evaporator 124 and/or may be disposed proximate the refrigerant line 169 or any other refrigerant line or component that may leak refrigerant into the conditioned space 112. The leak sensor 182 may also be located near a potential location where refrigerant may collect, such as near the floor of the conditioned space 112.

In response to the signal from the leak sensor 182 indicating a concentration of refrigerant greater than the threshold concentration or the signal indicating the presence of refrigerant within the internal volume 114, the controller 180 may perform leak mitigation as shown in the flow chart in fig. 4.

Referring to fig. 4, and with continued reference to fig. 3, a method 300 of leak detection in a refrigeration system 110 is illustrated, in accordance with an embodiment of the present disclosure. In an embodiment, the method 300 may be performed by the controller 180. At block 301, if the leak sensor 182 does not detect the presence of refrigerant or a refrigerant concentration greater than a threshold concentration, the method 300 may end and/or continuously check for refrigerant leaks repeatedly. If the leak sensor 182 detects the presence of refrigerant or detects a refrigerant concentration greater than a threshold concentration, the method 300 may continue to block 302. At block 302, the controller 180 may record the leak and the start of the leak mitigation strategy into memory. At block 304, the controller 180 is programmed to output an indicator for display. The indicator may be an audible indicator, a visual indicator, or the like. In at least one embodiment, the controller 180 may transmit information or data indicative of the leak to a driver, an operator, a remote computing system, a remote monitoring system, or a display.

The controller 180 may evaluate the operating states of various components of the refrigeration system 110 in parallel, substantially simultaneously, or sequentially. At block 342, the controller 180 may evaluate whether the main heating valve 196 is open. At block 342, if the main heating valve 196 is not open, the controller 180 will open the main heating valve 196 at block 354. At block 344, the controller 180 may evaluate whether the hot gas valve 194 is open. At block 344, if the hot gas valve 194 is open, the controller 180 will close the hot gas valve 194 at block 356. At block 346, the controller 180 may evaluate whether the condenser fan 158 is on and operating (e.g., running). At block 346, if the condenser fan 158 is not running, the controller 180 may command the condenser fan 158 to run at block 358. Operation of the condenser fan 158 may facilitate the shedding or dilution of the refrigerant proximate the condenser 122 if a leak occurs on the condenser side of the refrigeration system 110. At block 348, the controller 180 may evaluate whether the evaporator fan 168 is on and operating (e.g., running). At block 348, if the evaporator fan 168 is not running, the controller 180 may command the evaporator fan 168 to run at block 360. Operation of the evaporator fan 168 may facilitate the shedding or dilution of the refrigerant proximate the evaporator 124. At block 350, the controller 180 may evaluate whether the first valve 166 is open. At block 350, if the first valve 166 is open, the controller 180 will close the first valve 166 at block 362. At block 352, the controller 180 may evaluate whether the second valve 176 is open. At block 352, if the second valve 176 is closed, the controller 180 will open the second valve 176 at block 364.

At block 366, the controller 180 may evaluate whether the compressor 120 is on and operating (e.g., running). At block 366, if the compressor 180 is not on and operating, the controller 180 will run the compressor 180 before moving on to block 370. At block 370, the controller 180 may evaluate whether a suction pressure, such as a suction pressure less than ambient pressure, is present within the refrigerant line 169 extending between the evaporator 124 and the compressor 120. In such an embodiment, pressure sensor 190 is configured to detect the pressure within refrigerant line 169 and communicate the detected pressure to controller 180. At block 370, alternatively, the method may evaluate a fluid pressure within the evaporator 124 (e.g., an evaporator pressure) and determine whether the fluid pressure within the evaporator 124 is less than a threshold pressure. In such embodiments, the pressure sensor 190 is disposed within or proximate to the evaporator 124. If the suction pressure is less than the ambient pressure or the evaporator pressure is less than the threshold pressure, the method 300 may continue to block 372. If the suction pressure is greater than the ambient pressure or the pressure within the evaporator 124 is greater than the threshold pressure, the method 300 may return to block 366.

At block 372, the controller 180 may evaluate whether the second valve 176 is open. At block 372, if the second valve 176 is open, the controller 180 will close the second valve 176 at block 374 before moving on to block 376. At block 376, the refrigeration system 110 is turned off. The leakage mitigation strategy using the evacuation process greatly reduces the risk of the refrigerant reaching the lower flammability limit by removing the refrigerant from the evaporator 124 and storing it within the condenser 122. The leakage mitigation strategy may also dilute or disperse refrigerant that may be present within the interior volume 114 of the conditioned space 112. If the refrigerant leak is in a region not exposed to the interior volume 114, the refrigerant may dissipate by itself or with the aid of a condenser fan.

The term "about" is intended to include a degree of error associated with measuring a particular quantity based on equipment available at the time of filing the present application.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, element components, and/or groups thereof.

While the disclosure has been described with reference to one or more exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the essential scope thereof. Therefore, it is intended that the disclosure not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this disclosure, but that the disclosure will include all embodiments falling within the scope of the claims.

Claims

1. A refrigeration system, comprising:

a compressor driven by a power source, the compressor having a compressor outlet and a compressor inlet;

a condenser having a condenser inlet and a condenser outlet, the condenser inlet fluidly connected to the compressor outlet;

an evaporator having an evaporator inlet fluidly connected to the condenser outlet by a first valve movable between an open position and a closed position, and an evaporator outlet fluidly connected to the compressor inlet;

a leak sensor arranged to provide a signal indicative of refrigerant; and

a controller in communication with the first valve and the compressor, the controller arranged to receive the signal and programmed to command the first valve to move toward the closed position in response to the signal indicating the refrigerant.

2. The refrigeration system of claim 1, wherein the controller is further programmed to output an indicator for display.

3. The refrigeration system of claim 1, wherein the controller is further programmed to operate the compressor such that refrigerant within the evaporator is directed toward the compressor.

4. The refrigeration system of claim 3, wherein the controller is further programmed to command the compressor to cease operation in response to a fluid pressure between the evaporator outlet and the compressor outlet being less than a threshold pressure.

5. The refrigeration system of claim 3, further comprising:

a receiver having a receiver inlet fluidly connected to the condenser outlet, wherein the receiver is arranged to receive the refrigerant from the condenser.

6. The refrigeration system of claim 1, wherein the controller is arranged to receive the signal and is programmed to command the first valve to move toward the closed position in response to the signal indicating a selected concentration of the refrigerant.

7. The refrigeration system of claim 1, wherein the controller is further programmed to operate an evaporator fan upon detection of refrigerant.

8. The refrigeration system of claim 1, further comprising:

a second valve fluidly connecting the evaporator outlet and the compressor inlet, the second valve movable between an open position and a closed position.

9. The refrigeration system of claim 8, wherein the controller is further programmed to operate the compressor such that refrigerant within the evaporator is directed toward the compressor until a suction pressure measurement near an inlet of the compressor is less than ambient pressure.

10. The refrigeration system of claim 9, wherein the controller is programmed to command the second valve to move toward the closed position when the suction pressure measurement near the inlet of the compressor is less than ambient pressure.

11. The refrigeration system of claim 1, further comprising:

a main heating valve fluidly connecting the compressor outlet and the condenser inlet, the main heating valve movable between an open position and a closed position, wherein the controller is programmed to command the main heating valve to move to the open position.

12. The refrigeration system of claim 11, further comprising:

a hot gas valve fluidly connecting the compressor and the evaporator inlet, the hot gas valve movable between an open position and a closed position, and wherein the controller is programmed to command the hot gas valve to move to the closed position prior to commanding the first valve to move toward the closed position.

13. The refrigeration system of claim 8, wherein the evaporator and the leak sensor are located within a conditioned space of the refrigeration system, and wherein the first valve and the second valve are located outside the conditioned space.

14. A method of mitigating refrigerant leakage within a refrigeration system, comprising:

detecting a leakage of refrigerant from the refrigeration system;

closing a first valve to inhibit fluid flow of the refrigerant between an evaporator and a condenser fluidly connected to the evaporator; and

operating a compressor to direct another fluid flow of the refrigerant from the evaporator to the compressor.

15. The method of claim 14, further comprising:

directing the fluid flow of the refrigerant from the compressor to a receiver.

16. The method of claim 15, further comprising:

operating an evaporator fan disposed proximate to the evaporator.

17. The method of claim 15, further comprising:

stopping operation of the compressor in response to the evaporator pressure being less than a threshold pressure.

18. The method of claim 15, further comprising:

closing a second valve to inhibit fluid flow of the refrigerant between the receiver and the condenser.

19. The method of claim 14, further comprising:

closing a second valve to inhibit fluid flow of the refrigerant between the evaporator and the compressor.

20. The method of claim 14, wherein the method further comprises:

opening a main heating valve to allow fluid flow of the refrigerant between the compressor and the condenser; and

closing a hot gas valve to inhibit fluid flow of the refrigerant between the compressor and the evaporator.